Resumo
This paper describes the results of superimposing certain types of 5 x 5 latin squares on a wheat uniformity trial. The purpose was to investigate the bias in the estimate of error when certain systematic squares (knight's move and diagonal) are chosen and to compare the results under conditions in Brazil with those obtained by Tedin in a similar investigation. The following conclusions are drawn : a) when latin squares are chosen by a random process, as recommended by Fisher, the observed distribution of the variance ratio of "treatments" compared with error is i n agreement with that given by theory; b) the estimation of error variance is biased when systematic squares are employed. In agreement with Tedin, we find that the knight's move square furnishes an overestimate, and the diagonal square an underestimate of error variance. The results show that, under the conditions of our trial, the systematic squares suffer from the same disadvantages which have been noted elsewhere.
Disposição sistemática dos canteiros: sua influência sôbre a estimativa do êrro experimental
A. Conagin
Engenheiro agrônomo, Secção de Técnica Experimental e Cálculo, Instituto Agronômico de Campinas
SUMMARY
This paper describes the results of superimposing certain types of 5 x 5 latin squares on a wheat uniformity trial.
The purpose was to investigate the bias in the estimate of error when certain systematic squares (knight's move and diagonal) are chosen and to compare the results under conditions in Brazil with those obtained by Tedin in a similar investigation.
The following conclusions are drawn :
a) when latin squares are chosen by a random process, as recommended by Fisher, the observed distribution of the variance ratio of "treatments" compared with error is i n agreement with that given by theory;
b) the estimation of error variance is biased when systematic squares are employed. In agreement with Tedin, we find that the knight's move square furnishes an overestimate, and the diagonal square an underestimate of error variance.
The results show that, under the conditions of our trial, the systematic squares suffer from the same disadvantages which have been noted elsewhere.
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LITERATURA CITADA
- 1. Fisher, R. A. The arrangement of field experiments. Capítulo 17. Em Contributions to Mathematical Statistics, (pág. 503-513), John Wiley & Sons, New York, 1950.
- 2. Tedin, O. The influence of sistematic plot arrangement upon the estimate of error in field experiments. Journal of Agricultural Science 21 : 191-208. 1931.
Datas de Publicação
-
Publicação nesta coleção
07 Jun 2010 -
Data do Fascículo
Jul 1950
